Rence rawson



UNITED STATES ATENT FFICE,

FREDERICK L. RAWSON AND WILLIAM STEPNEY RAWSON, or LONDON,

ENGLAND. v v

PRODUCTION OF INCANDESdENT MANTLES.

SPECIFICATION forming part of Letters Patent No. 407,963, dated July 30, 1889.

Application filed August 21, 1888. Serial No. 283,360. (No model.) Patented in England September 1, 1886, No. 11,161; in Germany July 24, 1887, No. 43,012, and in France November 2, 1887, No. 186,722.

i To all whom, it may concern:

Be it known that we, FREDERICK LAW- RENCE RAWSON and WILLIAM STEPNEY RAW- sON, both subjects of the Queen of England, I residing at London, England, have invented certain new and useful Improvements in the Production of Incandescent Mantles, of which the following is a specification, and for which we have secured Letters Patent in Great Britain, No. 11,161, dated September 1, 1886; in Germany, No. 43,012, dated July 24, 1887, and in France, No. 186,722, dated November This invention relates to improvements in 1 the manufacture of mantles connected with the production of light by means of incandescence of refractory materials, known as the lVelsbach incandescent light, and the object of our improvement is to render these mantles after ignition sufficiently hard and resistant to allow of packing and handling without fear of breakage in the transport.

It is found that it is of the utmost importance that the mantles, which are to be rendered incandescent by the Bunsen burner, should be as regular as possible in their contour and also should be of slightly conical shape, so as to allow upon their surface. 1 stretching the mantles, which are composed of a knitted fabric impregnated with a soluthe flame to play evenly This is effected by tion of the earthy oxides, upon a platinum mandrel previous to ignition, and after lighting them from above and allowing them to -smolder down slowly we play a blow-pipe flame upon them with gradually-increasing force, so as to compel them to take the exact shape of the mandrel, which may be previously molded to any desired form. By these means the mantles are also raised to their full efficiency at once, which would otherwise require four or five hours burning over the usual Bunsen flame. The mantles having thus been given their proper shape at a higher temperature than they will afterward be raised to are less likely to lose their shape, and therefore their efficiency. The platinum foil of the mandrel should be of just sufficient .thickness to keep its shape, which can always be renewed by smoothing out upon a former. The heat of the blow-pipe will in this way be more easily kept up and not lost by the cool ing of the metal. The mantles may be stretched and treated upon the mandrel either before or after they are attached to the upright which supports them in the finished lamp. Difficulty has been found heretofore in the transport of these mantles without breakage, and various methods have been proposed. This difficulty our invention is designed to overcome by dipping the mantles, after they have been given their proper shape, into a liquid which will thoroughly penetrate the pores of the material and will afterward set to such a degree of hardness as to protect the material from danger of breakage in packing or handling, and which can afterward be removed without mechanical injury to the mantles or without leaving any objectionable residue.

lVe have found that a very satisfactory method of carrying out our invention consists in dipping the cone into a hot solution of volatile hydrocarbonsuch as benzinemixed with paraftine-wax or paraffine alone.

By these means the mantle in covered with a thin coating of wax, which becomes sufficiently hard on cooling to allow of packing and handling without fear of breakage. The paraffine is capable of burning away without any residue except carbon, which will always be burned completely away by the flame of the Bunsen burner. Vhen a hydrocarbon is used, it is merely for the purpose of dissolving the paraffine, and it is used in a sufficient quantity to form a liquid solution which will evaporate and leave the mantle coated with pal-affine. It is quite easytoignite the mantle from the top previous to placing it in 'position over the burner and allowing it to burn down, which it does somewhatafter the fashion of a candle and leaves no residue prejudicial to the lightgiving properties of the mantles. lVefind the following a suitable plan for combining the paraftine with the mantle: The par-affine is kept at a suitable temperature in a glass cylinder resting in a metal cylinder closely fitting it and containing oil,

which can be raised to high temperature The impregnation with paraffine also serves 3:

without giving off vapor. The mantle is then to protect the mantle from dust, which is of dipped into paraffine, and being slowly withgreat harm to it, for the dust which may addrawn the greater part of the parafline runs here to the parafiine-wax is entirely carried 5 off, and the only part holding an excess is the away when the paraffine is burned.

lower edge. This excess is best removed by What we claim is 3 5 wiping with a warm piece of glass, down 1. The hereindescribed improvement! in which the paraffine will run. While the lower strengthening incandescent mantles, consistedge is still pliable, and before the paraffine ing in coating the completed mantle with parhas hardened, we find it advisable to give the afiine or other suitable material, substantially l requisite shape to the mantle by carefully as set forth.

molding it over the rounded end of a glass 2. In the manufacture of incandescent test-tube of the right dimensions. Thus the mantles, themethod of forming said mantles, mantle assumes a perfectly-rounded shape which consists of first stretching the impregwhen the paraffiue sets hard, and quite suflinated knitted mantle upon a mandrel, then cient paraffine remains in the pores of the burning the mantle, then shapingthe mantle 45 netting to protect it from injury. against the mandrel by means of a blow-pipe Other materials may be employed as long flame, and finally coating the mantle with as they set hard at ordinary temperatures paraffin-e or other similar material, substanand burn away without mechanical destructially as set forth.

tion to the mantle and without leaving any In testimony that we claim the foregoing as 5 residue which would injure the light-giving our invention we have signed our names, in

properties of the mantle. presence of two witnesses, this 3d day of A11- The materials referred to as being capable gust, 188.8. y I q of use in lieu of paraffine may be any solid F. L. RAWSON.

hydrocarbon of a high boiling-point and many W. STEPNEY RAWS'ON. resins and gums soluble in spirit, such as Witnesses:

- alcohol, 4X60. Shellac will serve the samepur- ALFRED STEVENS,

pose, but not quite as advantageously. v O. DANNENBERG. 

